Known communication systems, of the type including postal shipping systems and postage meters, have a distributed customer base which includes a large number of devices at various customer sites. In such systems, it is necessary at various times to update information stored in some or all of the devices at some or all of the customer sites. For example, where zip codes, shipping rates, or postal rates change, all sites must be notified. On the other hand, in some environments, a change of a particular customer's address may be relevant only to some, but not all, of the other customers so that only some customer devices may require updating.
Such updating of information may be implemented by making the customer devices available to an update service managed by the communication system, such as by delivering the devices, or memory elements thereof, to a designated updating site. Alternatively, a system management representative may visit customer sites to provide the updated information. However, updating of information by delivery of devices to an updating site or by on-site visits from a customer representative is slow and expensive, and thus cannot be implemented frequently, so that devices at the customer sites may be operating with outdated information.
The prior art has addressed this problem and has provided techniques for updating devices at customer sites free of requirements for delivery of the devices to an updating site or for visits to the customer site by a customer representative. Thus, it is known in the prior art to use a central transfer station to contact remote customer systems, by modems for example, to download and upload information to and from the various customer systems, when the information is revised for example. The interconnection used in the prior art is illustrated in FIG. 1, where a central station 12 is shown as communicating with a number (e.g., fourteen) of devices 14 at various customer sites to update information stored therein.
In accordance with the configuration of the devices in FIG. 1, when postal rates change it is thus known to provide the new rates from the central transfer station to each of a plurality of customer systems, and particularly to those customer systems which include postage meters, in order to assure that the customers' meters print postage indicia of appropriate value on mail pieces of particular weight, size or dimension. When a change takes place in information which is relevant only to a subset of customer systems in the customer base, the central transfer station may provide the new information only to that subset of the set of all customer systems, but not to all such systems.
Thus, U.S. Pat. No. 4,122,532 discloses a system which updates obsolete postal rate data with new data, in which the new data are transmitted from a central data processor over phone lines directly to the remote mail processing devices.
In U.S. Pat. No. 5,222,018, there is described a system which receives shipping rate information at a shipper's premises and uploads the information to a central data processing facility, which in turn downloads the rate information to the various customers.
In U.S. Pat. No. 5,146,403, there is described a change of address system in which change of address terminals are widely distributed and in which a user provides address changes to the postal service, as well as to other users who send mail to that user.
The contents of each of the above described patents is incorporated herein by reference. In each of these systems there is provided direct transmission of data from one point to another on a one-to-one basis, which requires a transmission path to be established between the updating transfer (or transmitting) station and the customer (or receiving) station, and to be maintained during and throughout the transmission-reception (updating) operation.
However, when information is individually transmitted to a plurality of customer systems in accordance with the prior art one-to-one transmission configuration, the time required to complete an updating operation by a single transfer station grows at least linearly with the number of devices of the customer base which are being updated, thus requiring an increasingly complex transmission facility in the central transfer station and an increasing expense for implementing such an updating service.
U.S. Pat. No. 5,455,865, the contents of which are incorporated herein by reference, addresses the concept of routing information packets among nodes interconnected by links to form a network. The patent describes alternate approaches to transmitting a packet from a source node to a destination node. The packet may either be broadcast to every node on the network, so that the intended destination node will ultimately receive the packet, or may be routed directly to the destination node via a specific group of nodes connecting the source to the destination node.
In the broadcast method, a flooding technique is described, wherein each node which receives a packet of information is required to transmit the packet to each of its neighboring nodes (except the node from which the packet was received) so that, sooner or later, by one route or another, the packet arrives at its intended destination. In a single routing method for the packets, a source node assembles information indicating the relationships of the nodes and links, and identifies an entire route to a destination node for a particular information packet. Thus, a source node launches a packet to any destination node by providing a neighbor node with the packet and with destination, or routing, information. The neighbor (and each subsequent node receiving the packet) makes an independent decision as to which is the next node to which the packet should be forwarded in order to reach the specified destination node.
However, the flooding technique provides duplicate transmissions and the single routing approach continues to rely on a single connection path from a source node to each destination node, for each packet transmission, albeit using intermediate nodes and supplying routing information to the intermediate nodes. That is, the source node is required to initiate a transmission operation for each transmission to each destination node so that resources of the source node continue to be heavily utilized as the number of destination nodes grows.
Thus, the prior art imposes a heavy burden on the resources of a central station when the central station is used as a source node for communications with a large number of destination nodes. More specifically, none of the above described systems reduces the number of operations required to be carried out, and thus the time used, by a central transfer station when transferring update data to a plurality of destination nodes.
In order to reduce expenses associated with updating of devices at a large number of customer sites, as well as to permit a central station acting as a source node to continue to serve a growing number of destination nodes, it is necessary to provide a more efficient, less expensive, and quicker approach than used in the prior art to propagate information, and particularly to propagate common information, from a central transfer station to a number of customer sites.
Moreover, particularly for systems used in transmitting postal information which is used in printing value on mail pieces, it is necessary to assure a high level of accuracy when implementing a technique of more efficient and faster transmission of information from a central station to a plurality of customer sites.
Thus, there is a particular need in the prior art for an arrangement which more quickly propagates information from a central transfer station to a plurality of customer sites.
There is still a more specific need in the prior art for a method and apparatus capable of transmitting update information from a central transfer station to a large number of customer sites with reduced involvement of the central station while providing assurance to the central station that information so transmitted is accurately received, and for providing correct information in the event that an error is determined to have occurred in the transmission.